Schizotricha crassa Pena Cantero and Vervoort 2004

Schizotricha crassa Peña Cantero and Vervoort, 2004

Schizotricha crassa Peña Cantero and Vervoort 2004a, p 30 –32, Figure 1.

Material examined. 12/1003, one stem fragment ca 50 mm long, with gonothecae (USNM 1012901); 575/061, numerous unbranched stems up to 220 mm high, with gonothecae (USNM 1012902, RMNH-Coel. 30915, MNCN 2.03 /313); 575/070, two broken stems (largest fragment ca 130 mm long), with gonothecae (holotype, USNM 1012900; paratype, RMNH-Coel. 30916); 575/074, one basally truncated stem ca 150 mm high (USNM 1012903); 7/499, several stem fragments up to 105 mm long, with gonothecae (USNM 1012904, RMNH-Coel. 30917).

Diagnosis. Colonies with unbranched stems. Main cauline tube with single hydrothecate internodes with two to five infrathecal nematothecae and occasionally with extra suprathecal nematotheca. Without node between cauline apophyses and hydrocladia; occasionally, however, present and then cauline apophyses with two or three nematothecae. Hydrocladia up to 12th order. Hydrocladia divided into hydrothecate internodes. Unforked hydrocladial internode with one or two infrathecal nematothecae at approximately same level. Hydrotheca deep. Forked hydrocladial internodes with one to three infrathecal nematothecae; hydrocladial apophyses with two or three nematothecae.

Remarks. The material of this species was previously described and figured by Peña Cantero and Vervoort (2004a). Schizotricha crassa is characterized by the usual absence of a node between cauline apophyses and hydrocladia, the strong development of perisarc, the angle of ca 90 u formed by the cauline apophyses, the high degree of hydrocladial branching, the strongly arched structure of the hydrocladia which, due also to the acute angle formed by the cauline apophyses, stand on the same side of the stem, and the characteristic shape of the male gonothecae, which have a relatively long and thin basal chamber.

Sometimes double hydrocladial internodes are present, provided with two hydrothecae, each with the typical set of nematothecae.

Ecology and distribution. Schizotricha crassa was collected at depths from 93 to 238 m. Fertile colonies were found in March, May and June. It is used as a substratum by Sertularella sp. Schizotricha crassa seems to be endemic in West Antarctica, having been collected NE of Joinville Island, in the Antarctic Peninsula area, south of the South Orkney Islands, and off Visokoi and Zavodovski Islands, in the South Sandwich Archipelago (cf. Peña Cantero and Vervoort 2004a).